Part of the Year 2000 goals include reduction of dietary fat to less than 30% of total energy with increased intake of fruits, vegetables, and whole grain products to yield 20g or more of dietary fiber per day. This proposal is for a randomized clinical trial of a self-help intervention to promote lower fat and higher fiber dietary patterns. There will be 735 participants randomized into two study arms: Personalized Self-Help, a program based on self-help materials augmented with personalized motivational and behavioral feedback; and Usual Care, no intervention. Intervention components will be based on key concepts of social learning theory: increasing motivation, self-efficacy, and nutritional knowledge and skills. The personalized motivational messages will vary based on participants' stage of readiness for dietary change, and the personalized behavioral feedback will vary based on participants' usual dietary habits. Participants will be recruited from new enrollees to Group Health Cooperative, a large health maintenance organization, and all recruitment and assessment activities will be over the telephone. Evaluation will be based on a combination of dietary assessment tools selected to minimize bias and respondent burden, yet allow detailed analyses of dietary behavior changes. Primary endpoints will be contrasts in intervention group-level changes in percentage of energy from fat and grams of fiber, based on unannounced, 24-hour dietary recalls completed at baseline and 12 months post-intervention. Secondary endpoints will include changes in fat- and fiber-related dietary habits assessed at baseline, 3 months and 12 months, with an additional assessment at 18 months to evaluate long-term durability of dietary change. A subsample of 100 participants per arm will receive additional dietary and psychosocial assessments to support comprehensive process analyses and validity studies. The study will evaluate the effectiveness of a comprehensive, self-help intervention when delivered to a representative sample from a defined and generalizable population. The intervention developed and tested in this proposal would be suitable for delivery by health care insurers, employers, or community groups.